January 17, 2015

Updated History and Photos of Japanese Submarines After WWII

The following is based the excellent Japanese document "History of the Japanese Submarine (After WWII)". It used to be at http://www3.ocn.ne.jp/~y.hirama/yh_e_papers_sub_f.htmlbut it seems a dead link "404 not found" now. The document seems to precede introduction of the first Soryu-class submarine that entered Japanese Navy service in 2009.

The document pointed to no author. However I am advised by an Anonymous commenter that the original author of this document is Dr Yoichi Harama, Former Professor of the National Defense Academy of
Japan.

As the original document only went to 2006 I am steadily updating it for the period 2007 through to January 2015. I'm also improving some of the grammar. Grateful for any suggestions - particularly about the current and future Soryus. Pete.--------------------------------------------

History of the Japanese Submarine (After WWII)

Model of Japan's latest submarine class - the Soryu

Defense Plan and Submarines

Japan had constructed 242 submarines in the Imperial navy era (1869 - 1945), and operated 3530 ton (6560 ton submerged) I-400 submarine carry three floatplanes during the World War II. However, 58 submarines that remained with the defeat in 1945 were taken over by the Allies Forces and have been dismantled or sunk in the Pacific Ocean.

By outbreak of the Korean War in June 1950, the National Police Reserve(Later Ground Self-Defense Force) was born in August. While, in April 1952 the Maritime Security Force was organized in the Maritime Safety Agency, and in August the Maritime Self-Defense Force(Hereafter JMSDF) was reformed from the Maritime Security Force and independent from the Maritime Safety Agency.

During the cold war era, the mission of the JMSDF was aimed the command of the sea of the west Pacific in cooperation with the U.S. navy, against Soviet navy as one of the west side navy, influenced by the confrontation between the east and west. But after surrender the Pacific War, as Japan was enforced by the Allied Occupation Forces to accept the constitution, which declared renunciation of war, as a sovereign right of the nation and the threat or use of force as means of settling international disputes. By this historical background, and strong anti-military feeling among the peoples, the National Defense Council draw up the Basic Policy for National Defense and it was approved by the Cabinet in May 1957. This policy declared Japan has been making efforts on its own initiative to build a modest defense capability under the Constitution in accordance with the fundamental principals of maintaining an exclusively by defense-oriented policy of not becoming a military power that might pose a threat to other courtiers. Though the Maritime Self-Defense Force esteemed to strengthen operational capability of anti-submarine and mine sweeping operation as allies that the U.S. navy is lacking in the northeast Asia area.

By this defense policy, the main mission of the JMSDF submarine was surveillance and interception of Soviet combatants in major straits. In order to ensure the safety of Japan’s maritime transportation, the JMSDF needs to maintain the posture capable of deploying two submarines each in the three straits of Soya, Tsugaru and Tsushima, where necessary. In order to maintain such capability, it was necessary to possess six divisions with 16 submarines, taking into account geographical relations between submarine bases and sea areas where engage in surveillance and interception operation.

However, early stages of the 1950s, there were strong opposition to have submarine by left wing political party and peoples. They opposed that submarine is an aggressive weapon and violate what is called “Peace Constitution”. By these oppositions, the construction of the submarine was delayed in comparison with the surface combatants, such as a destroyer and escort ship. So, the JMSDF had to ask the assistance for the U.S. navy for the target submarine needed for ASW training. Then fleet type submarine Mingo(SS-261) of U.S. navy was lent, on the basis of the Japan-U.S. Weapon Loan Agreement that was concluded in August 1955 and she was turn-over to the JMSDF and named Kuroshio(SS-501).Thus after 10 year’s interval of defeat of the Pacific War, Japanese new navy ? the JMSDF could hosted the Rising?Sun flag again to the sale of the submarine.

Thereafter, Kuroshio carry our the duty as the underwater target boat and submarine’s crew OJT(On the Job training) ship, as the sole submarine of the JMSDF for about 5 years until the first domestic submarine come out and take over this role. As there was very strong anti-military feeling among peoples of Japan, the JDSDF could not use the word of submarine, so it was called as “an underwater high-speed target” for budge requirement and public announcements. These feeling still continued and Japanese submarines are still imposed several fateful restriction from the time of the birth to nowadays.

From FY1958 to FY1977, the JMSDF was reinforcing by Five Years Defense Built-up Program four times, accordance with the Basic Policies for National Defense. This Basic Policies for National Defense include an exclusively defense-oriented policy, and also, adherence to the Three Non-Nuclear Principles, -- “Japan do not make or use any nuclear weapons and do not permit to bring into any nuclear weapon in Japanese territories”, also maintaining firmly the Japan - U.S. security arrangements.

But in 1970s there aroused the strong opinion that Japan should restrict armament accordance with the world situation of the U.S and Soviet peace talk, the National Defense Policy and National Defense Buildup Program Outline were reviewed in October 1976. Further more as a result of the collapse of the Soviet Union, the defense power of the necessary minimum as an independent state which means not to become over the unstableness in our country periphery and self "becomes the blank of power” was decided by the National Defense Council and approved by the Cabinet in November 1995. Accordance with this new National Defense Buildup Program Outline, first Mid-Term Defense Built-up Plan (FY1980-FY1983) was adopted in December 1979.

By this new National Defense Buildup Program Outline, defense capabilities and major units and main equipment of the JMSDF were again reviewed, and due to the deterioration of finances, necessary expenses were significantly reduced in December 1997. The submarine forces were also reviewed by this new National Defense Buildup Program Outline, but six divisions sixteen submarines were maintained, thought about 10% of the JMSDF forces were reduced by the policy of streaming, making it more efficient and compact.

However, at that time it was difficult to achieve 20 knots submerged underwater due to lack of space for large sufficiently powerful engines. Finally the 1000 tons option was adopted in December 1957 by the Maritime Staff Office. Construction of Oyashio began at the Kawasaki Heavy Industries Ltd (KHI). Kobe Shipbuilding Yard from December 1957. Oyashio was launched in May 1959 and after half year’s sea trial, Oyashio was commissioned in June 1960, as the name of Oyashio (SS-511).

During construction there were many difficulties partly because Japan had not built a submarine since 1945. The basic design was adopted from the high-speed WWII I-201 class. Oyashio was 1,157 tons surfaced, 79 m long, diesel 2750 horsepower, 6000 horsepower and 19 knot submerged. WWII Imperial Navy technology such as the automatic depth holding system was adapted, but the snorkel and other new devices were introduced from the U.S. navy. Technicians and and submariners visited the US Navy, and learned not only technology, but also submarine operation and tactics.

The JMSDF learn from the U.S. navy and also the submariners were tamed to the devices and system of the U.S navy through the Kuroshio, so if there was not big difference between Japan and America, applied the U.S. navy’s methods. During the construction increased 130 tons, and finally displacement became 1130 tons. She equipped four tubes for 533mm torpedoes. Power system was diesel-electric, two diesel Kawasaki MAN type of V8V22/30MATL, 2700 horsepower, two main motors of 5900 horsepower and two shaft, speed was 13 knot on surface, 19 knot in underwater , the battery was 4 groups of 120 cells. NS 46 high tension steel was used in hull, this high tension steel NS46 means 46kg pressure on 1mm square.

On that time, as there were no training facilities for submariners in Japan, there aroused a demand to dispatches submarine to Hawaii to use the U.S. navy’s training facilities, and to learn tactics. This training is continued from 1968 to now and expanded to the LimPac Exercise including not only submarines, but also surface ships and air plain to improve tactical level and closer relations between the JMSDF and the U.S. navy.

Remarks 1:The name of submarine of the JMSDF was name after from oceanographic phenomenon of “Shio(Tide)” in JapaneseRemarks 2: Submarine is constructed at the ex-Imperial navy’s main submarine Contractor of the New Mitsubishi Heavy Industries Kobe and the Kawasaki Heavy Industries Kobe alternately at a rate of one per two years in fiscal year.

The plans for next submarine Hayashio (SS-521) above begin with 700 tons but it become 750 tons, and first Hayashio class boats begin construction in June 1960 at New Mitsubishi Heavy Industry Kobe and lunched in June 1962, other was constructed by Kawasaki Heavy Industry in Kobe in June 1960 and also lunched in June 1962, and two more Natsushio class boats constructed in 1963. Hayashio class was firstly esteemed for coastal defense and for blocking the three straits as a attack-submarine(SSK) in war time, and also aimed to be under-water target submarine for ASW training in the peace time.

The speed decreased 14 knot in submerged with 2300 horsepower and surface 11 knot with 900 horsepower. Battery system was 120 shell and 2 groups. Due to the small boat, torpedo tubes were limited only six, but from this class hydrographic launching tubes were introduced from air launching tubes. Also from this class, two sonar systems were adopted, one is passive bow sonar, and the other was active sonar under the sail covered by FRP dome for ranging. The big difference of Hayashio and Natsushio is length, from Natsushio class canning tower were expanded 1.5 m for astern and overall length became 59m to 61m and displacement increased 790 tons.

The JMSDF constructed three classes of ten submarines by the First(FY1958 - FY1962) and the Second (FY1962 ? FY1967) Defense Built-up Programs. But, as Hayashio was constructed after long blank of construction, there were many malfunctions and troubles, and that Hayashio class was too small for stable snorkeling in the rough sea around Japan, and also as restricted in endurances capability because of poor habitability. By theses reasons, small size submarine 750 ton class were not considered in Japan after Hayashio class. Hayashio class constructed 4 boats,

From operational experiences of small submarines, these small submarines were lacking operational stability in the rough sea, especially in snorkeling. Next submarine was considered for large multipurpose submarine for patrol, surveillance, reconnaissance and crew’s training. Ooshio/Oshio class above went to the sea in March 1965, then Asashio of 1650 tons improved type of Ooshio was commissioned in October 1966.

By enlargement of displacement, eight 533mm torpedo tubes in bow and two short range homing torpedo tubes in stern which aimed as the counter-attack for anti-submarine ships(Later short range torpedo tubes were take off). Bow Torpedo tube became from air pressure launching to hydraulic launching. New steering and engines automation systems and auto-course holder were adapted. From this class provided a steering system became aircraft type stick control at the diving stand.

This class was expected, as an underwater target use, so boat was esteemed high speed to carry out may services with a few submarines, so compromised with 18 knots in underwater with main motor of 6300 horsepower, 14 knot on surface with Man V8V24/30AMTL 2900 horsepower, two shafts. From these reasons underwater performance as a submarine was not realized until appearance of tears drop submarine. The L/D ratio become 11,7 in this class while Hayashio class was 9,2. From Asashio class screw propeller become 5 blades and safety depth increased by high tension steel NS 46.

Uzushio class was the historic mile stone for the Japanese submarine that changed the application of the submarine which esteemed the surface ability than underwater ability. Ten kinds of models were made, to design the hull that demonstrated underwater performance, and conducted the water tank experiment to collect data for design of submarine figure and could get tears drop type submarine with one axis, L/D changed from conventional submarine 11,7(Oyashio class) to 7,1 in tear drop type. Also, the development of new steel necessary to expand safety depth was started.

First boat of the Uzushio class began construction in January, 1971 and seven boats were constructed in the Third Defense Build-up Programs (FY1967-FY1972), and the Fourth Defense Build up Programs (FY1972-FY1977). By the adoption of tears drop type, underwater performance increased largely in comparison with the conventional submarine. Power plant was diesel-electric propulsion with two Kawasaki MAN V8V24/30AMTL diesel engines and speed was 12 knot by 3400 horsepower, output of main electric motor was 7200 horsepower, and estimated speed was 20 knot pulse in the under water. Battery became 240 set 2 groups from this class.

New high tension steel NS63 was used on hull to increase the safety submerge depth to 300m(est). Increased tonnage brought space, deck becomes three layers, and this improved not only habitability of performance but also could equipped many devices. Carbonic acid gas absorbent air cleaner, the emergency blow system(Main blow tank), installation of spare torpedo, and could equipped the steerage device, trim and depth adjustment automatic controller, automatic direction holder, and automatic steerage of three dimensions.

From the Uzushio class increased tonnages to 1850 ton, torpedo tube in bow was removed to the mid-ship section to install large sonar ZQQ-1 in bow(from Isoshio ZQQ-2, from Takashio ZQQ-3), also plane removed from bow to the sail. This plane arrangement was characteristic of the teardrop style submarine. In Japan, when the Uzushio was commissioned (in 1971), some members of the opposition pursued an issue in the Diet that the JMSDF was aiming to use nuclear propulsion for submarine and that this was contrary to the "The three Non-Nuclear Principles". This stemmed from the belief that if an engine was nuclear powered the submarine would become a nuclear submarine easily.

Yushio class submarine was the second generation of tear-drop boats, from FY1975 to FY1985, 10 boats were constructed. This class is double hull structure and used new high tension steel NS80 and safety depth increased 400m(est). The main engines are Kawasaki MAN V8V24/30ATMTL type, 12 knot at snorkel, and 20 knot in the water. From this class, high capacity new battery were installed, screw rotation are lower than Asashio class with five blades husky propeller. Automatic steerage system of three dimensions, automatic depth and direction holder system were equipped. VLF communication was also possible, net-work-centric combat systems were incorporated in operation room, which enhance adaptability of operations.

The reason why Japanese submarine increased displacement constantly are installation of many kind of the weapons aiming a various functions for one submarine, as the total number of submarines are limited within 16 by the National Defense Buildup Program Outline. By this limitation, the JMSDF must decommissioned all boat which passed 16 years then assigned reserve, consequently all Japanese boat served sixteen years of front line, then assigned an axially training submarine for three years, then scraped and finished 19 years life. Furthermore as Japan strictly adopts a firm policy of banning prohibiting the exportation of a submarine or any weaponry, so mass production of auxiliaries equipments are push up high price because of small production, this also enforced effective usages of defense expenditures and oppressing defense budget.

The Harusio class is the third generation of the tear-drop submarine construction began from FY1986 to FY1992, and seven boats were constructed. Harushio class followed fundamentally adapted design of Yushio class, but increased 250 tons in displacement. This type was esteems improvement of the underwater maneuverability, expanded search and attack ability. The main motor’s rotation is slower than Yushio class with seven blades high-skew propeller.

The various measures have been carried out to improve noise and tried to make silent submarine cut on noise of not only main engines but also auxiliary machines. Main engines and main motor were fitted on emission double anti-vibration rubber to reduce of a noise, pipe system, gears, and gaskets were improved, and also snorkel noise are reduced. Harushio class became a considerably quieter boat adapting noise-cut in auxiliary machines, while underwater speed, underwater endurances, safe submerge depth are greatly improved. High tension steel NS110 is adopted with a double shell hull and safety depth is extended 500 m(est). New inverter of electric power transformation(CVCF), which transform of 400 Hz and 60 Hz of the power supply, this help noise reduction and also saving electric power. From this type, torpedo/USM tubes were equipped from constriction stages, fitted with ZQQ-5 sonar system(From Nadashio ZQQ-5B type) combined with TASS and side-array-sonar as a unit. The reception of the communication became possible at the submerged states by the introduction of VLF receiver.

Oyashio class is the successor of the Yushio class, and the first submarine of the cigarette type submarine in the JMSDF. While planing Harushio, there began two studies for next submarine. One is material for secrecy from active sonar to absorb reflection. Another is automatic steering, trim control system which were also carried out in parallel in these studies. From 1991 to 1992, integrates submarine operation(Fire control) system was discussed by the Next Term Submarine Technology Examination Committee, member of a committee was Technical, Equipment, Defense Department of MSO, Submarine Fleets and Technology Research Center. These studies are applied to new tactical integrated operation(fire control) system.

From this class to improve search ability, new ZQQ-5(from Michishio ZQQ-5B, Makishio ZQQ-6) sonar was equipped in bow and passive detecting sonar was top of the sail. Also developed array sonar fitted on hull and TASS sonar was fitted astern part. By these sonars capability of the detection in a long-distance was greatly expanded. Main engine is same as Harushio class, but output of main motor is increased 550 horsepower. From Arashio(SS-586) screw changed 5 to 7 blades with high-skew propeller. For weapon new 89 type torpedo and six torpedo/USM(Harpoon) combined tube are in bow and two automatic mine launchers are fitted on stern part. The big different of Oyashio class is changed hull structure to the simple shell partly from double shell with new high tension steel NS110. Torpedo tubes in bow were removed to mid-ship section, and for anti-detection stealthy for reflection hull is slanted and also sail is covered noise absorptive tile. Main engine is same as Harushio, Kawasaki 12V25/25S, but output power increased 550 horsepower.

Construction of the first Oyashio class began January 1994, and commissioned in March 1998, and now six are in active and more two are under construction. During construction, in 2000 from Uzushio (SS-594) the solid aminn carbonic acid gas absorption device was adopted, and from Isoshio(SS-593) floating antenna was introduced. From 1960 to now the JMSDF constructed 40 diesel powered submarine, 10 were pre-tear-drop type boats, 24 were tear-drop type boats and 6 were cigarette type boats. But as there is the restriction of "The Non-Nuclear Three principle", nuclear engines are not allowed to use, so the JMSDF started next population Project of the AIP (Air Dependent Propulsion) engine from 2000, installing Stirling engine of the Swedish Kockums Co. ITD. , fitted on Asashio (TSS-3601) and started test from December, 2001.

TheSōryū-class
submarines(16SS)
are diesel-electric submarines that entered service with theJapan Maritime Self-Defense Forcein 2009. The design is an evolution of theOyashio class submarine, from which it can
most easily be distinguished by its X-shaped tail planes. TheSōryūshave the largest displacement of any
submarine used by post war Japan.

At 84 m long
and 4,200-tons submerged, Soryu is significantly larger than the original 11
Oyashio-class boats (81 m and 3,500 tons), in order to incorporate a Kockums
Stirling air independent propulsion (AIP) system. With the Kockums Stirling AIP
system the submarine doesn't have to surface to charge the batteries and thus
increases the submerged endurance from days to weeks. Components for the AIP,
which will enhance the vessel's stealth and special operations capability, were
supplied by the Swedish company for assembly in Japan.

The Soryus design features higher automation (particularly in
combat systems) and computer-aided X control planes. The revolutionary X rudder
configuration was first developed by Kockums for the Swedich Gotland-class. The X rudder
provides the submarine with extreme manoeuvrability and also enables it to
operate very close to the seabed. The Soryu's hull is clad in anechoic coating
and the interior features sound isolation of loud components. An anechoic
coating has a major effect on the avoidance of detection.

The Soryu was was launched at Mitsubishi Heavy
Industries (MHI's) Kobe shipyard on December 2007 and commissioned in March 2009. It was formerly known as the
"SS 2,900 ton" and the "16SS" project as it originated in
the 16th year of the current Emperor's reign (2003).

The cost of the sixth Soryu ( the "Kokuryu") was estimated at 540 US$ million.

Japanese submarines since
World War II were named afterocean
currents. However, the JMSDF changed itsnaming
conventionwith theSōryuand submarines
will now be named after mythological creatures.Sōryū(そうりゅう) means blue (or green) dragon in Japanese.

The Soryus are envisaged to be a class of ten. As at January 2015 five AIP equipped Soryus (which I call Soryu 1s) had been Commissioned. One more AIP Soryu/Soryu 1 is due to be Commissioned in March 2015. While the first six Soryus (SS-501 to SS-506) utililize AIP the Soryus from SS-507 onwards are expected to be "improved" Soryus . The "improved" Soryus are expected to have no AIP, no lead-acid bateries, but instead Lithium-ion batteries. I call these improved Soryus "Soryu 2s". One report of September 29, 2014 indicates: "Six of 10 Soryu-class submarines which take about four years
to build...have been completed. Japan’s Defense Ministry has just
requested 64.4 billion yen (US $589.5 million) to start building [four Soryu 2s, starting with SS-507] from April 2015, and this — and three other boats —
will use Lithium-ion batteries."

SORYU TABLESee regular SORYU TABLE updates on Submarine Matters - latest update is on November 6, 2017 with 26SS being named Shyuriyu. Soryu 16SS can be called "Soryu Mark 1s" with Stirling AIP. Future Soryu 28SS can be called "Soryu Mark 2s" with no Stirling AIP but they will have Lithium-ion batteries (LIBs).

* LAB means Lead Acid Battery, LIB is Lithium-ion Battery, AIP is Air Independent Propulsion29SSwill be a new submarine class (no longer called Soryu). New features for the Next-Generation Submarine - 29SS - may include:

- A more effective and powerful snorkel generation system for recharging the LIBs.

- A next generation sonar system

- Introduction of the Next-Generation heavyweight torpedo known as G-RX6.

- An improved platform to reduce vibrations. This platform will be more impact resistant.

Submarine Organization

In February, 1960 in accordance with the increase of submarines, submarine base was opened at Kure in the Inland Sea of western part of Japan, in there Kure Submarine Education Department was established as the attachment of the Kure Submarine Base. In 1961 submarine rescue ship ASR Chihaya (1340 tons diving bell type) was commissioned and in August 1962, the First Submarine Division was formed to conduct submarine operation and submarine rescue operation. In February, 1965 accordance with increase of submarines, the First Submarine Division reformed to the First Submarine Flotilla.

In 1981 along with the reinforcement of the submarines, the Submarine Fleet was newly formed in Yokosuka, under the Self Defense Fleets with the 1st and 2nd submarine Flotilla, the Submarine Education and Training Division(SETD) and the 1st Submarine Training Division. The Submarine Fleet commander is responsible to all operations of submarine including the submarine rescue activity and also unification of submarine tactics. Each submarine flotilla consists of a submarine base and 2 or 3 submarines divisions. The Submarine Flotilla Commander is type commander and responsible to the training, the Submarine Base commander is responsible for logistics support.

Submarine Education and Training Division(Kure Base) has a detachments in Yokouska, Submarine Education and Training Division has Submarine diving simulation trainer, Submarine Tactics Simulatio Trainer and navigation Simulation trainer which help level up of tactical skill. Yokosuka Tactics Support Division (YTSD) operate DSRVT (Deep Submergence Rescue Vehicle Trainer) for rescue crew of DSRV craft. The escape training installation and fire-water fighting facility located at the First Service School (Etajima) in the Inland Sea, opposite side of the Kure Submarine Base.

Submarine Organization Chart (at March 28, 2015)Note that Japan intends to expand its submarine fleet to 22 active submarines - in doing so creating a new Division.

No comments:

Submarine Matters

Director, Submarine Matters International. I analyse international trends, technical and political - mainly on submarines, sometimes on surface ships, aircraft, missiles and their nuclear warheads. This website started in 2007. I have a Masters Degree (International Relations (Strategic Studies)) High Distinction average. I'm happy to do research projects commissioned by consultancies, etc. The best way to navigate this site is to put a keyword in the search box top left corner.